The invention concerns an implantable orthopedic device with a load-bearing element such as a bone plate, with at least one opening for a fixation element such as a bone screw. An insert is provided that can be inserted into the opening in a receptacle in which the external shape of the insert is at least partially complementary to the internal shape of the receptacle. The insert has a central through-bore for mounting a body of the fixation element. The implantable orthopedic device has a structure for holding the insert in the receptacle.
A series of implantable orthopedic devices with load-bearing elements, such as bone plates, with openings for the insertion of fixation elements in such load-bearers are known from the prior art. Among them are proposals for the mono-axial as well as poly-axial attachment of fixation elements, particularly screws.
As an example for a device of this type having poly-axial attachment of screws in load-bearing elements is shown in U.S. Pat. No. 5,954,722. Other bone plates with inserts are shown in U.S. Pat. Nos. 5,976,141 and 5,607,428.
Among the proposals in the prior art is WO 00/53110 (U.S. Patent Publication No. 2002/0045901) which publication relates to an elongated bore in a load-bearing element, which is, on one end, semicircular with rounded-off edges, and which exhibits on the opposing end what essentially is a half thread. The threaded end extends at an angle of more than 180 degrees. With this, it is possible to screw a screw into the threaded side at right angles to the load-bearing element, so that the screw is also firmly connected to the load-bearing element. On the opposite side of the bore, it is possible to screw in a screw at a desired angle perpendicular to the load-bearing element, particularly poly-axially. These screws are, however, not stably locked in the axial direction.
The prior art exhibits the disadvantage that the screws are intended exclusively for insertion with specifically designed load-bearing elements, and thus only a specific type of insertion, such as, for example, poly-axial attachment or mono-axial attachment, is possible. Inserts for bone plates are known from U.S. Pat. No. 5,190,545.